Viewshed (location)

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// Copyright 2018 Esri.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
// You may obtain a copy of the License at: https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific
// language governing permissions and limitations under the License.

using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.Controls;
using Esri.ArcGISRuntime.UI.GeoAnalysis;
using System;
using System.Drawing;
using System.Windows;
using System.Windows.Input;
using Point = System.Windows.Point;

namespace ArcGIS.WPF.Samples.ViewshedLocation
{
    [ArcGIS.Samples.Shared.Attributes.Sample(
        name: "Viewshed (location)",
        category: "Analysis",
        description: "Perform a viewshed analysis from a defined vantage point.",
        instructions: "Use the sliders to change the properties (heading, pitch, etc.), of the viewshed and see them updated in real time.",
        tags: new[] { "3D", "frustum", "scene", "viewshed", "visibility analysis" })]
    public partial class ViewshedLocation
    {
        // Hold the URL to the elevation source.
        private readonly Uri _localElevationImageService = new Uri("https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer");

        // Hold the URL to the buildings scene layer.
        private readonly Uri _buildingsUrl = new Uri("https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/Buildings_Brest/SceneServer/layers/0");

        // Hold a reference to the viewshed analysis.
        private LocationViewshed _viewshed;

        // Hold a reference to the analysis overlay that will hold the viewshed analysis.
        private AnalysisOverlay _analysisOverlay;

        // Graphics overlay for viewpoint symbol.
        private GraphicsOverlay _viewpointOverlay;

        // Symbol for viewpoint.
        private SimpleMarkerSceneSymbol _viewpointSymbol;

        // Flag indicating if the viewshed will move with the mouse.
        private bool _subscribedToMouseMoves;

        // Height of the viewpoint above the ground.
        private double _viewHeight;

        public ViewshedLocation()
        {
            InitializeComponent();

            // Initialize the sample.
            Initialize();
        }

        private void Initialize()
        {
            _viewHeight = HeightSlider.Value;

            // Create the scene with the imagery basemap.
            Scene myScene = new Scene(BasemapStyle.ArcGISImageryStandard);
            MySceneView.Scene = myScene;

            // Add the surface elevation.
            Surface mySurface = new Surface();
            mySurface.ElevationSources.Add(new ArcGISTiledElevationSource(_localElevationImageService));
            myScene.BaseSurface = mySurface;

            // Add the scene layer.
            ArcGISSceneLayer sceneLayer = new ArcGISSceneLayer(_buildingsUrl);
            myScene.OperationalLayers.Add(sceneLayer);

            // Create the MapPoint representing the initial location.
            MapPoint initialLocation = new MapPoint(-4.5, 48.4, 46 + _viewHeight);

            // Create the location viewshed analysis.
            _viewshed = new LocationViewshed(
                initialLocation,
                HeadingSlider.Value,
                PitchSlider.Value,
                HorizontalAngleSlider.Value,
                VerticalAngleSlider.Value,
                MinimumDistanceSlider.Value,
                MaximumDistanceSlider.Value);

            // Create a camera based on the initial location.
            Camera camera = new Camera(initialLocation, 200.0, 20.0, 70.0, 0.0);

            // Create a symbol for the viewpoint.
            _viewpointSymbol = SimpleMarkerSceneSymbol.CreateSphere(Color.Blue, 10, SceneSymbolAnchorPosition.Center);

            // Add the symbol to the viewpoint overlay.
            _viewpointOverlay = new GraphicsOverlay
            {
                SceneProperties = new LayerSceneProperties(SurfacePlacement.Absolute)
            };
            _viewpointOverlay.Graphics.Add(new Graphic(initialLocation, _viewpointSymbol));

            // Apply the camera to the scene view.
            MySceneView.SetViewpointCamera(camera);

            // Create an analysis overlay for showing the viewshed analysis.
            _analysisOverlay = new AnalysisOverlay();

            // Add the viewshed analysis to the overlay.
            _analysisOverlay.Analyses.Add(_viewshed);

            // Add the analysis overlay to the SceneView.
            MySceneView.AnalysisOverlays.Add(_analysisOverlay);

            // Add the graphics overlay
            MySceneView.GraphicsOverlays.Add(_viewpointOverlay);

            // Update the frustum outline Color.
            // The frustum outline shows the volume in which the viewshed analysis is performed.
            Viewshed.FrustumOutlineColor = Color.Blue;

            // Subscribe to tap events. This enables the 'pick up' and 'drop' workflow for moving the viewpoint.
            MySceneView.GeoViewTapped += MySceneViewOnGeoViewTapped;
        }

        private void MySceneViewOnGeoViewTapped(object sender, GeoViewInputEventArgs geoViewInputEventArgs)
        {
            // The viewshed observer is picked up and moving. Drop it.
            if (_subscribedToMouseMoves)
            {
                MySceneView.MouseMove -= MySceneViewOnMouseMove;
            }
            // The viewshed observer is currently pinned. Pick it up.
            else
            {
                MySceneView.MouseMove += MySceneViewOnMouseMove;
            }

            // Toggle the viewshed movement flag.
            _subscribedToMouseMoves = !_subscribedToMouseMoves;
        }

        private void MySceneViewOnMouseMove(object sender, MouseEventArgs mouseEventArgs)
        {
            // Get the mouse position.
            Point cursorSceenPoint = mouseEventArgs.GetPosition(MySceneView);

            // Get the corresponding MapPoint.
            MapPoint onMapLocation = MySceneView.ScreenToBaseSurface(cursorSceenPoint);

            // Return if the MapPoint is null. This might happen if mouse leaves SceneView area.
            if (onMapLocation == null)
            {
                return;
            }

            // Adjust the Z value of the MapPoint to reflect the selected height.
            onMapLocation = new MapPoint(onMapLocation.X, onMapLocation.Y, onMapLocation.Z + _viewHeight);

            // Update the viewshed.
            _viewshed.Location = onMapLocation;

            // Update the viewpoint symbol.
            _viewpointOverlay.Graphics.Clear();
            _viewpointOverlay.Graphics.Add(new Graphic(onMapLocation, _viewpointSymbol));
        }

        private void HandleSettingsChange(object sender, RoutedEventArgs e)
        {
            // Return if viewshed hasn't been created yet. This happens when the sample is starting.
            if (_viewshed == null)
            {
                return;
            }
            // Calculate the difference between the old and new height.
            double difference = HeightSlider.Value - _viewHeight;

            // Update the view height value to the new value.
            _viewHeight = HeightSlider.Value;

            // Move the viewshed to the new height.
            _viewshed.Location = new MapPoint(_viewshed.Location.X, _viewshed.Location.Y, _viewshed.Location.Z + difference);

            // Update the viewshed settings.
            _viewshed.Heading = HeadingSlider.Value;
            _viewshed.Pitch = PitchSlider.Value;
            _viewshed.HorizontalAngle = HorizontalAngleSlider.Value;
            _viewshed.VerticalAngle = VerticalAngleSlider.Value;
            _viewshed.MinDistance = MinimumDistanceSlider.Value;
            _viewshed.MaxDistance = MaximumDistanceSlider.Value;

            // Update visibility of the viewshed analysis.
            _viewshed.IsVisible = (bool)AnalysisVisibilityCheck.IsChecked;

            // Update visibility of the frustum. Note that the frustum will be invisible
            //     regardless of this setting if the viewshed analysis is not visible.
            _viewshed.IsFrustumOutlineVisible = (bool)FrustumVisibilityCheck.IsChecked;

            // Update the viewpoint graphic.
            _viewpointOverlay.Graphics.Clear();
            _viewpointOverlay.Graphics.Add(new Graphic(_viewshed.Location, _viewpointSymbol));
        }
    }
}